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08-24-2010, 07:42 PM   #1
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1.4x Teleconverter for Pentax K7 and smc PENTAX DA Star 200mm F2.8 ED (IF) SDM

I am looking for a quality 1.4x teleconverter that will function with my Pentax k7 and smc PENTAX DA Star 200mm F2.8 ED (IF) SDM lens. From what I have read the Tamron 1.4X Pz-AF MC4 will work, but it looks to be discontinued.

Do you have a teleconverter you could recommend to me? I do not want to lose any functionality of my current combination.

Thanks!
Steve

08-25-2010, 08:52 AM   #2
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Hello,

No, I am sorry. There are currently no tele-converters that we have tested that will work with the 200mm lens.

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08-25-2010, 10:25 AM   #3
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Interesting. What are the chances that Tamron discontinued the production of the 1.4X Pz-AF MC4 by request of Pentax via some type of deal they struck? I can see how the Tamron 1.4x would put a huge damper on Pentax's 300mm F4 sales since you would basically have the same lens with a 200mm and teleconverter, only with more versatility.

This is all very frustrating to say the least.........
08-25-2010, 10:59 AM   #4
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QuoteOriginally posted by imagesforyou Quote
Interesting. What are the chances that Tamron discontinued the production of the 1.4X Pz-AF MC4 by request of Pentax via some type of deal they struck? I can see how the Tamron 1.4x would put a huge damper on Pentax's 300mm F4 sales since you would basically have the same lens with a 200mm and teleconverter, only with more versatility.

This is all very frustrating to say the least.........
FWIW, I would say that the chances Pentax had anything to do with the 1.4x Pz-AF being discontinued is pretty much zero

I've owned the DA*200, DA*300 and the Tamron 1.4x Pz-AF (several copies actually) and while the DA*200 works with the 1.4x, the AF performance was ok at best. In addition, the IQ of the DA*300 is at least a step above the DA*200+1.4x.

The other option is the Pentax F 1.7x AF Adapter. The upside is that it uses it's own screw-driven AF and is very quick. The downside is that you lose the full range of AF. If I recall correctly, with a longer lens like the DA*200, so long as you leave it manually focused close to infinity, the 1.7x AF Adapter can pretty much focus the entire range. For very close-up shots you would need to manually focus it closer, but for most shots over 5-10ft (again, if I recall corecctly) you can leave the focus ring in one place.

08-25-2010, 07:18 PM   #5
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Thanks for the feedback dgaies. What is your opinion of the 1.7x IQ? I will be using this setup for outdoor sports action shots 80% of the time. My 200mm doesn't always get me where I need to be and I end up doing extensive crops, which lessons the IQ. For that reason, the focusing issue you referred to should rarely be a problem for me.

---------- Post added 08-25-10 at 09:34 PM ----------

dgaies, is this the adapter you are referring to?

japan exposures | films and more (formerly Megaperls Japan Webshop)

Looks like they are rare, but possibly available.
08-25-2010, 08:24 PM   #6
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QuoteOriginally posted by imagesforyou Quote
Thanks for the feedback dgaies. What is your opinion of the 1.7x IQ? I will be using this setup for outdoor sports action shots 80% of the time. My 200mm doesn't always get me where I need to be and I end up doing extensive crops, which lessons the IQ. For that reason, the focusing issue you referred to should rarely be a problem for me.

---------- Post added 08-25-10 at 09:34 PM ----------

dgaies, is this the adapter you are referring to?

japan exposures | films and more (formerly Megaperls Japan Webshop)

Looks like they are rare, but possibly available.
They are somewhat rare, but not too hard to find. I actually have one that I never really use since getting rid of my long primes DA*200 and DA*300 (I haven't really used it on the DA*60-250).

The IQ with the 1.7x is pretty good. I found it works especially well with primes, not only because you end up with a higher final IQ, but also because of the way the 1.7 AFA reports aperture info (and doesn't report focal length) to the camera. Basically the 1.7x automatically converts the aperture data so when you adjust the aperture on the camera body, it has already taken the 1.5 stops lost to the TC into account.

Also, with the 1.7 attached, the camera will prompt you to enter a focal length. While this might sound like a bad thing since you have to manually enter it, it's actually a very good thing as you can input the corrected focal length and the in-body SR system will use that value. The downside is that with a zoom you can only enter a single value so you either have to enter the value you'll be using the most or split the difference and choose a value in the middle of the range.

Perhaps someone else can chime in if they disagree, but for outdoor sports I would think the 1.7x AF Adapter would be a better choice than the Tamron 1.4x (on an SDM lens) since the AF is going to be a lot faster and more reliable. The AF is probably faster with the 1.7x AF Adapter than without it using only the SDM focusing.

Not sure if that answered all of your question... let me know if you have any others or feel free to PM me.
08-25-2010, 09:50 PM   #7
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Thanks again for your time dgaies. I can see how the 1.7 AFA would work nice with primes given it reports the correct aperture info. Does the Tamron 1.4x not do this?

This may be a stupid question, but given the resulting aperture when the AFA is attached, does the depth of field equal what it would if a straight prime (no AFA attached) were used of the same resulting aperture and focal length? I hope that makes sense........
08-26-2010, 03:39 AM   #8
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QuoteOriginally posted by imagesforyou Quote
Thanks again for your time dgaies. I can see how the 1.7 AFA would work nice with primes given it reports the correct aperture info. Does the Tamron 1.4x not do this?

This may be a stupid question, but given the resulting aperture when the AFA is attached, does the depth of field equal what it would if a straight prime (no AFA attached) were used of the same resulting aperture and focal length? I hope that makes sense........
No, the Tamron 1.4x does not do this, it just pass through the aperture data through to the body (as do pretty much all TCs that report aperture data at all AFAIK).

Again, someone can correct me if I'm wrong, but I am pretty sure the DOF on the prime+TC combo is the same as if it were the on uncorrected aperture (the actual aperture set on the lens). So I am pretty sure you will have less DOF with the prime+TC at a given equivalent focal length and aperture than you would with a longer prime of the equivalent focal length and aperture.


Last edited by dgaies; 08-26-2010 at 03:54 AM. Reason: clarification
08-26-2010, 04:49 PM   #9
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I have the Tamron 1.4x Pz teleconverter. Its important that the TC have the "powerzoom" contacts, as that is what SDM uses for power. Rule of thumb is that a 1.4x TC costs 1 stop of light, 2x costs 2 stops of light. My DA 300 works fine with the 1.4X and the sharpness is OK to me on 100% crops. 2 months ago i used the combination on a whale watching trip and it worked fine.

Although not available new, i've seen about 4 of those TCs in the last few months on the Marketplace, so they come up occasionally. With people bailing for FF cameras, its a good time to pick one up :-) Pentax previously committed to a TC i believe, it'll be interesting at photokina if they commit to one.

Last edited by philbaum; 08-26-2010 at 05:49 PM.
08-26-2010, 05:23 PM   #10
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Hi!
Just my own experience:

I have both the Tamron 1.4x Pz teleconverter and the A-FA 1.7X Pentax adapter.
Since I acquired the Pentax one, I have not used the Tamron a single time.... Oh! ... yes I did, once only with my Tamron 70-200/2.8.

The IQ of the 1.7X adapter, mounted with the DA*300/4 is very good, if not great. I took me quite a while to get used to go "manual focusing" and letting the adapter do its magic though. I admit not using it often enough, probably because I end up shooting in less than adequate lighting conditions very often. But I find that it is very fast and accurate with proper exposure.
Under good lighting, such as during a bright morning, the combo I have described above works without a glitch.
And, if I remember correctly, the 1.7X TC plus the DA*300/4 will give me a maximum aperture of 6.3 (or is it 6.7? ... ); anyway, this tells you right away that it isn't perfect for low light conditions, especially when one needs faster shutter speeds. ... repeating myself here.

Hope that helps.

JP
08-27-2010, 08:38 PM   #11
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I want to give a heads up that just because a TC has the pz contacts doesn't automatically make it SDM compatible, especially with the DA* 300/4 and DA* 60-250/4.
08-28-2010, 10:38 AM   #12
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QuoteOriginally posted by Blue Quote
I want to give a heads up that just because a TC has the pz contacts doesn't automatically make it SDM compatible, especially with the DA* 300/4 and DA* 60-250/4.
That's true, from what I've read, just having pz contacts isn't enough. However, I think all the Tamron 1.4x Pz-AF MC4 will work fine (FWIW, I've had 5 different copies of that TC and they all worked with my SDM lenses).
08-28-2010, 07:49 PM - 2 Likes   #13
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I have the Tamron 1.4x Pz-AF MC4 and it worked fine with all my lenses. If you want to try one before your buy let me know I'll send you mine and you can test it on your lenses and send it back. Just send me a PM and let me know.
09-02-2010, 05:57 PM   #14
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Have been wanting a AF working TC for my DA*200F2.8 since i got it. I got that lens based on what the Australian Pentax importer, (CRKennedy) told me. "Yes you will be able to use a 2x TC with AF on this lens"

Have found out this is wrong.

Is about time Pentax put out a working AF TC for it's cameras and lenses..

Need a 500mm+ lens for my surfing/nature shots, without spending $6000.
09-02-2010, 08:16 PM   #15
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Is this it?

Is this the infamous Pentax F 1.7x AF Adapter?

Amazon.co.jp: HOYA F AFアダプタ1.7X F AFアダプター1.7X: 家電・カメラ

It goes for about $350 on Amazon Japan, and shows they ship in 3-4 days (so I assume they have them in stock).

Can someone confirm for sure that this adapter works with the Pentax DA*200/2.8?

I did a bit of reading and it seems the DOF may follow the increase in aperture setting with the addition of the adapter (more DOF in other words). Can someone confirm this?

Thanks!
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